8. Psychotropic medication use (including benzodiazepines and illicit drugs) during the 21 days (42 days for fluoxetine) prior to the PET scan. The exception would be 1-5 doses of 0.5-1.0mg of benzodiazepine (lorazepam (Ativan)) by mouth, separated by at least 24 hours between doses, for anxiety related to study procedures.